1. Field of the Invention
The present invention relates to a light emitting device and a bulb-type LED lamp.
2. Description of Related Art
A traditional filament bulb has a diffusion film formed on a glass bulb (a globe) for controlling the glare in order to prevent a high intensity of a point light source from causing a discomfort feeling on humans. In the meantime, a bulb-type fluorescent light has a light emitting property that an entire lamp emits fluorescent light, and therefore glaring can easily be controlled.
On the other hand, taking advantage of high-power output and high-efficiency technologies of light emitting diodes (LEDs), light bulbs that uses an LED as a light source are put into practical use in recent years. Meanwhile, an LED has a small-sized light source, and its brightness is extremely high, and furthermore it has a light emitting property that it radially emits light in certain directions. Therefore, when being used as a light source of a light bulb, it is difficult for an LED to diffuse light uniformly all over a globe.
To solve the difficulty described above, proposed in Patent Document 1 is an LED light bulb equipped with a diffusion sheet placed on an external surface of a translucent globe, the LED light bulb being able to nearly homogenize its brightness.
Patent Document 1: JP 2008-91140 A